Yang Zhilin, Li Yan, Li Zhipeng, Wu Deyin, Kang Junyong, Xu Hongxing, Sun Mengtao
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603-146, Beijing 100190, People's Republic of China.
J Chem Phys. 2009 Jun 21;130(23):234705. doi: 10.1063/1.3153917.
Surface enhanced Raman scattering (SERS) of pyridine adsorbed on Au@Pd core/shell nanoparticles has been investigated theoretically with quantum chemical method, generalized Mie theory and three-dimensional finite-difference time domain (3D-FDTD) method. We first studied the influence of the coated Pd on the electronic structure of Au nanoparticle, and compared the electronic structure of Au(20) cluster with that of Au(10)Pd(10) (core/shell) cluster. Second, we studied SERS spectroscopy of pyridine on Au@Pd core/shell nanoparticles, which revealed the rate of static chemical enhancement and electromagnetic enhancement in the experimental reports. Third, the influence of the Pd shell thickness to the optical absorption of Au@Pd core/shell nanoparticles was investigated with generalized Mie theory. Fourth, we studied the influence of the shell thickness to the local electric field enhancement with 3D-FDTD method. The theoretical results reveal that the static chemical enhancement and electromagnetic enhancement are in the order of 10 and 10(3), respectively. These theoretical studies promote the deeper understanding of the electronic structure and optical absorption properties of Au@Pd, and the mechanisms for SERS of molecule adsorbed on Au@Pd.
采用量子化学方法、广义米氏理论和三维时域有限差分（3D-FDTD）方法，对吸附在Au@Pd核壳纳米颗粒上的吡啶的表面增强拉曼散射（SERS）进行了理论研究。我们首先研究了包覆的Pd对Au纳米颗粒电子结构的影响，并比较了Au(20)团簇与Au(10)Pd(10)（核/壳）团簇的电子结构。其次，我们研究了吡啶在Au@Pd核壳纳米颗粒上的SERS光谱，该光谱揭示了实验报告中的静态化学增强和电磁增强速率。第三，用广义米氏理论研究了Pd壳层厚度对Au@Pd核壳纳米颗粒光吸收的影响。第四，用3D-FDTD方法研究了壳层厚度对局部电场增强的影响。理论结果表明，静态化学增强和电磁增强分别约为10和10(3)。这些理论研究促进了对Au@Pd电子结构和光吸收特性以及吸附在Au@Pd上的分子的SERS机制的更深入理解。
